Priestly celibacy is not a dogma. It is merely a practice. It is not somethign we believe is revealed as a truth which all must ascribe to. Rather, it is merely our way of doing things.
You may be unaware, but there exist entire branches of the One Catholic Church which have priests who are married. Not in this country, but in the East. We couldn't very well do that if it was a dogmatic belief that priests must be celibate, right?
As for the rest, your wording about Mary aside (who considers having someone to pray with you an "obligation"? Do you feel "obliged" to pray with your fellow Christians? Is it a burden?), the rest are indeed dogmatic beliefs.
An example of an open area that is not dogmatic is the question of what happens to infants who die prior to being baptised.
SD